Recover data from External Hard drive

Try recuva.

http://www.piriform.com/recuva

I personally use several freeware recovery utilities since there doesn't seem to be any one surefire solution to data recovery.

Here's one solution that I have personally tried with successful results:

http://www.techyv.com/questions/how-can-i-recover-my-formatted-hardisk-data#comments

Aside from Minitool Power Data Recovery, Piriform's Recuva is also a good and simple to use file recovery tool.

Success of recovery depends on how much you used the hard drive since you reformatted it. If you haven't used it yet after it got reformatted, then the chances of recovery are higher.